Quantum dot-sensitized solar cell and method of making the same

Abstract

The quantum dot-sensitized solar cell (QDSSC) includes a photoelectrode, a counter electrode, and an electrolyte sandwiched between the photoelectrode and the counter electrode. The photoelectrode is formed from a titanium dioxide (TiO2) layer, a cadmium sulfide (CdS) quantum dot sensitizer layer, and a tin dioxide (SnO2) nanograss layer sandwiched between the titanium dioxide (TiO2) layer and the cadmium sulfide (CdS) quantum dot sensitizer layer.

We claim: 
     
       1. A method of making a quantum dot-sensitized solar cell, comprising the steps of:
 providing a photoelectrode, the photoelectrode being made by the steps consisting of:
 applying a titanium dioxide paste on a fluorine-doped tin oxide substrate; 
 heating the titanium dioxide paste and the fluorine-doped tin oxide substrate to form a mesoporous titanium dioxide electrode; 
 growing tin dioxide nanograss on the mesoporous titanium dioxide electrode using chemical bath deposition to form a pre-loaded electrode, wherein growing the tin dioxide nanograss on the mesoporous titanium dioxide electrode comprises the steps of:
 mixing SnCl2.H2O and hexamethylenetetramine to form a tin dioxide growth solution; 
 dipping the mesoporous titanium dioxide electrode in the tin dioxide growth solution; and 
 heating the mesoporous titanium dioxide electrode and the tin dioxide growth solution; 
 loading cadmium sulfide quantum dots on the pre-loaded electrode using successive ionic layer adsorption and reaction cycles to form a photoelectrode, wherein each said ionic layer adsorption and reaction cycle comprises:
 dipping the pre-loaded electrode in an aqueous Cd(CH3COO)2.2H2O solution; 
 rinsing the pre-loaded electrode with ethanol; 
 dipping the pre-loaded electrode in a Na2S solution; and 
 rinsing the pre-loaded electrode with ethanol; 
 
 
 
 providing a counterelectrode; and 
 sandwiching an electrolyte between the photoelectrode and the counter electrode. 
 
     
     
       2. The method of making a quantum dot-sensitized solar cell as recited in  claim 1 , wherein the step of heating the titanium dioxide paste and the fluorine-doped tin oxide substrate comprises heating the titanium dioxide paste and the fluorine-doped tin oxide substrate at 450° for 30 minutes. 
     
     
       3. The method of making a quantum dot-sensitized solar cell as recited in  claim 1 , wherein the step of loading the cadmium sulfide quantum dots on the pre-loaded electrode comprises eight successive ionic layer adsorption and reaction cycles. 
     
     
       4. The method of making a quantum dot-sensitized solar cell as recited in  claim 1 , wherein the counter electrode is a copper sulfide counter electrode. 
     
     
       5. The method of making a quantum dot-sensitized solar cell as recited in  claim 1 , wherein the step of sandwiching the electrolyte between the photoelectrode and the counter electrode comprises sandwiching a polysulfide electrolyte between the photoelectrode and the counter electrode.